1. Field of the Invention
The present invention generally relates to network switching. More specifically, the present invention provides techniques for effectively and efficiently mapping frames for transmission between Layer 2 Virtual Local Area Networks and external networks.
2. Description of Related Art
A Layer 2 Virtual Local Area Network such as a Metro Ethernet network provides mechanisms for setting up virtual local area networks so that individual local area networks can be seamlessly integrated into a wide area network. An individual node in a first local area network can communicate with a node in a second local area network as though the two nodes were in the same local area network. Metro Ethernet networks allow effective intercommunication between nodes in disparate local area networks.
However, communication with nodes outside of the Metro Ethernet network is limited. For example, to establish communication with an external Internet Protocol (IP) network, each local area network would have to set up separate communications with this external network. In another example, to establish communication with an external ATM network, again each local area network would have to set up links to the ATM network. For communication with external ATM networks, an RFC 1483 bridge can be used to connect individual local area networks with an ATM network. However, a RFC 1483 bridge has scalability limitations.
Consequently, it is desirable to provide techniques for improving the mechanisms and techniques for communications between Metro Ethernet networks and external networks.